First ultrasound measuring behind?

Hey everyone. So I had my first OB appointment today. I didn’t have a doctor yet because I just moved to a new state, so I made an appointment with the woman’s clinic at the hospital I work at. They would only schedule me to see an NP so I went today, and it went absolutely terrible. She had nothing important to say to me (other than a few random things that are common knowledge about pregnancy) and was quite offended that my husband and I didn’t know on the spot if we wanted to do genetic testing or not. I’m currently 6w6d so was expecting a transvaginal ultrasound (and was even scheduled for one on my charting app), but she said all she “had time for” was an abdominal one. On the scan all that we could see was a gestational sac & an yolk sack, but it was measuring 5w1d. This was obviously concerning to me but she brushed me off and said it was fine because we “didn’t know for sure when my last period was” even though I know the exact date of my period & the day I ovulated… I’m just wondering if anyone has also measured behind? Or if it being abdominal could have anything to do with it? Also, not sure if it’s worth noting, but the ultrasound machine she used literally looked like it was from prehistoric times. Just looking for some advice/input because now i’m stressed about a miscarriage.